Patients who received a bioengineered protein during spinal fusion procedures to correct neck pain had far more complications than patients who did not get it, according to a study released Tuesday.

The study published Tuesday found that patients who had received the bioengineered proteins during spinal fusions for lower or middle back pain did not have increased complications when compared with those who did not get the product. But complications rates while patients were still in the hospital were 50 percent higher for cervical fusions procedures, researchers reported.

Dr. Kevin S. Cahill, a neurosurgeon at Brigham and Women’s, who led the study released Tuesday, said he believed the complication rates for the cervical fusion procedures were actually higher than those reported in the study because complications often occurred after a patient left the hospital.